The present invention relates generally to compositions and their formation and use, and more particularly relates to a polishing solution for chemical-mechanical polishing (xe2x80x9cCMPxe2x80x9d) for forming an integrated circuit.
In CMP, a substrate assembly is positioned on a CMP pad located on a platen or web. By substrate assembly, it should be understood to include a substrate having one or more layers and/or features formed thereon and/or therein. A wafer carrier is used to apply a downward force to push the substrate assembly against the CMP pad. The CMP pad and the substrate assembly are moved against, and relative to, one another, while applying the downward force to effect material removal. Polishing solution, containing polishing particulate to facilitate material removal, is dispensed on the CMP pad. The polishing solution conventionally is chemically reactive to remove unwanted material more rapidly than other material on the substrate assembly. This chemical reactivity may be changed during CMP processing.
Accordingly, CMP may be used to planarize a surface of a substrate assembly. Furthermore, CMP may be used to remove a layer of material in order to expose an underlying layer. Conventionally, the underlying layer is a xe2x80x9cstopxe2x80x9d layer. By xe2x80x9cstopxe2x80x9d layer, it is meant CMP for the underlying substance significantly slows removal of material; in other words, the CMP process is selective to the underlying layer or substance.
A polishing solution is described in U.S. Pat. No. 5,738,800 to Hosali et al. In Hosali et al., a polishing solution is described as having an aqueous medium, abrasive particles (xe2x80x9ccolloidal ceriaxe2x80x9d), a surfactant (xe2x80x9cpotassium hydrogen phthalatexe2x80x9d or xe2x80x9cKHPxe2x80x9d), a compound which complexes with silicon dioxide (xe2x80x9csilicaxe2x80x9d or xe2x80x9cSiO2xe2x80x9d) and silicon nitride (xe2x80x9cSi3N4xe2x80x9d), and a composition to adjust pH levels (xe2x80x9cpotassium hydroxidexe2x80x9d or xe2x80x9cKOHxe2x80x9d). Thus, such a solution may be adjusted to have a substantially neutral pH. By substantially neutral pH, it is conventionally meant a pH in a range of about 6.0 to 6.5.
Two pH neutral adjusted polishing solutions from Rodel of Newark, Del., under the names of CSC5105-DV and CSC5005-ES were used in CMP processes to form shallow-trench isolation (xe2x80x9cSTIxe2x80x9d) structures in substrate assemblies. The substrate assemblies were being processed to provide a plurality of dynamic random access memories (xe2x80x9cDRAMsxe2x80x9d) having a memory array with about a 210 nm half-pitch. However, there were a significant number of defects, such as scratches, in the substrate assemblies.
Hence, there is a need in the art, especially the art of high-density (210 nm or less half-pitch) integrated circuit manufacture, to provide a polishing solution and process for CMP which reduces the amount of defects.
It has been discovered by the inventors herein that by adding surfactant to form polishing solution the above-mentioned defects could be reduced. Moreover, it was discovered that by mixing surfactant, abrasive particles, and etchant in various premix and/or point of use mix combinations, differing outcomes would result.
Accordingly, the present invention provides composition and method of formation and use therefor in CMP. More particularly, a polishing solution comprising abrasive particles, etchant, and surfactant is provided, as well as methods of formation and use thereof. The polishing solution may further comprise one or more liquid mediums. An ionic or a nonionic surfactant may be used. More particularly, the nonionic surfactant may be a polyoxyethylene, such as a polyoxyethylene ether or a polyoxyethylene ester. Various embodiments for combining abrasive particles, etchant, and surfactant by point of use mixing, premixing, and combinations thereof are described herein with associated settling and turbidity rates.